Can someone help me with this ixl question?

How do you use the elimination method for this question? explain, because i really want to understand!

Find the least common denominator for thesetvo rational expressions.n^2/n^2+4n+4 -3/n^2+7n+10

Consider a bag that contains 220 coins of which 6 are rare indian pennies. for the given pair of events a and b, complete parts (a) and (b) below. a: when one of the 220 coins is randomly selected, it is one of the 6 indian pennies. b: when another one of the 220 coins is randomly selected (with replacement), it is also one of the 6 indian pennies. a. determine whether events a and b are independent or dependent. b. find p(a and b), the probability that events a and b both occur.